Effect of color contrast on visual lobe shape characteristics.

This study examined the effects of the color contrast of target and background objects on visual lobe area and shape characteristics. For visual lobe mapping the participants had to locate a single colour target amongst a homogeneous background of non-targets during a brief presentation. Targets of six different colors (red, yellow, green, cyan, blue, purple) were tested, the non-targets were black and the background was metallic grey. The results showed that color contrast did not affect visual lobe parameters under the constant luminance contrast condition of 6:1 tested in the experiment. Subjective preference evaluations showed that the blue and purple targets resulted in the highest visual comfort and overall preference, respectively, while the yellow target was the most negatively rated. The color preferences here were somewhat different from the previous color combination studies. It might be due in part to the constant luminance contrast and display polarity used here.

Effect of display polarity and luminance contrast on visual lobe shape characteristics.

The effect of display polarity and luminance contrast on visual lobe (effective visual field) shape characteristics was studied using three levels of luminance contrast with combinations of positive and negative polarities. The binocular effective visual field for a detection task, with a peripherally presented target (V) embedded in a homogeneous competing background (Xs), was mapped on 24 imaginary axes passing through the fixation point. The results showed that visual lobes mapped using positive polarity were statistically larger in area, rounder and more regular in shape than those for negative polarity. The medium contrast condition lobes were more symmetric and regular than low contrast condition lobes, and lobe area and perimeter increased with increasing luminance contrast ratio. Under the interaction of positive polarity and high luminance contrast, visual lobes were found to be larger, smoother and rounder. The high level of luminance and contrast however resulted in a higher degree of visual discomfort. The results indicated that positive polarity and contrast of medium (26:1) to high (41:1) levels are possible display settings for better visual lobe characteristics and better anticipated search performance. Practitioner Summary: The effect of display polarity and luminance contrast on visual lobe shape characteristics was examined with uniform stimulus materials in this study. The results help to identify the optimum display settings for luminance contrast and display polarity to enhance lobe shape characteristics and hence search performance in industrial inspection tasks.

Development of a real-time control strategy with artificial neural network for automatic control of a continuous-flow sequencing batch reactor.

The purpose of this study is to develop a reliable and effective real-time control strategy by integrating artificial neural network (ANN) process models to perform automatic operation of a dynamic continuous-flow SBR system. The ANN process models, including ORP/pH simulation models and water quality ([NH4(+)-N] and [NOx(-)-N]) prediction models, can assist in real-time searching the ORP and pH control points and evaluating the operation performances of aerobic nitrification and anoxic denitrification operation phases. Since the major biological nitrogen removal mechanisms were controlled at nitrification (NH4(+)-N-->NO2(-)-N) and denitritification (NO2(-)-N-->N2) stages, as well as the phosphorus uptake and release could be completely controlled during aerobic and anoxic operation phases, the system operation performances under this ANN real-time control system revealed that both the aeration time and overall hydraulic retention time could be shortened to about 1.9-2.5 and 4.8-6.2 hrs/cycle respectively. The removal efficiencies of COD, ammonia nitrogen, total nitrogen, and phosphate were 98%, 98%, 97%, and 84% respectively, which were more effective and efficient than under conventional fixed-time control approach.

Dynamic control of a continuous-inflow SBR with time-varying influent loading.

The conventional sequential control of Sequencing Batch Reactor (SBR) is designed with fixed time periods for various operation phases. However, both of the flow rates and qualities of influent vary over time, therefore, a big capacity of wastewater equalization unit is required to cope with influent variability. Such an equalization unit increases the total treatment costs of the system, especially in a small-scale wastewater treatment system. Moreover, in using a SBR treating a time-varying influent loading with conventional sequential control, the system performance cannot be optimized. This paper presents the application of on-line ORP and pH monitoring to dynamically control a continuous-inflow SBR with time-varying loading of influent flow rates and water qualities. Experiential results show that the dynamic controlled SBR revealed not only achieved better substrate removal efficiencies, but also reduced treatment costs.

Cytogenetic monitoring of petrochemical workers.

The frequencies of chromosomal aberrations and sister-chromatid exchanges (SCEs) in the peripheral blood lymphocytes of 360 persons, 180 workers in a petrochemical corporation and 180 appropriate controls, were studied. A significant increase in chromosomal aberrations and SCEs, compared to the control group, was observed in two sewage-treatment workshop workers; however, there were no significant differences between petrochemical workers from four workshops and a control group.